Use of calcium binding proteins to improve cardiac contractile function

Methods useful in the regulation of myocardial contraction are disclosed. The methods are useful in the regulation of heart function. The invention reveals that sorcin overexpression enhances cardiac contractile performance and establishes the concept of sorcin as a regulator of myocardial contractility. The invention also provides screening assays that allow for the identification of agents that modulate sorcin expression. Such agents are useful, for example, for diagnosing cardiac contractile function associated disorders in subjects, and treating the subjects with the agents identified as being able to modulate sorcin expression.